Day #55 Deskcrop: Glomeroporphyritic Basalt

Today’s deskcrop features a rather uncommon and distinctive glomeroporphyritic texture. It appears that the plagioclase phenocrysts in this rock nucleated at a small number of sites and grew into the surrounding magma in a radial pattern. Perhaps it should come as no surprise that the common name for rocks with this texture is “Daisy Stone”. This sample is a Keweenawan-aged basalt from the Algoma region of Ontario, though I’m intentionally putting its placemark in Lake Superior to protect the specific locality.